Bluetooth: Fix/implement Three-wire reliable packet sending

This patch should complete the necessary code for sending reliable
Three-wire packets.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

drivers/bluetooth/hci_h5.c

@@ -64,15 +64,15 @@ struct h5 {
 	struct sk_buff		*rx_skb;	/* Receive buffer */
 	size_t			rx_pending;	/* Expecting more bytes */
 	bool			rx_esc;		/* SLIP escape mode */
+	u8			rx_ack;		/* Last ack number received */
+	u8			rx_seq;		/* Last seq number received */
 
 	int			(*rx_func) (struct hci_uart *hu, u8 c);
 
 	struct timer_list	timer;		/* Retransmission timer */
 
-	bool			txack_req;
-
-	u8			next_ack;
-	u8			next_seq;
+	bool			tx_ack_req;	/* Pending ack to send */
+	u8			tx_seq;		/* Next seq number to send */
 };
 
 static void h5_reset_rx(struct h5 *h5);
@@ -89,7 +89,7 @@ static void h5_timed_event(unsigned long arg)
 	spin_lock_irqsave_nested(&h5->unack.lock, flags, SINGLE_DEPTH_NESTING);
 
 	while ((skb = __skb_dequeue_tail(&h5->unack)) != NULL) {
-		h5->next_seq = (h5->next_seq - 1) & 0x07;
+		h5->tx_seq = (h5->tx_seq - 1) & 0x07;
 		skb_queue_head(&h5->rel, skb);
 	}
 
@@ -138,6 +138,45 @@ static int h5_close(struct hci_uart *hu)
 	return 0;
 }
 
+static void h5_pkt_cull(struct h5 *h5)
+{
+	struct sk_buff *skb, *tmp;
+	unsigned long flags;
+	int i, to_remove;
+	u8 seq;
+
+	spin_lock_irqsave(&h5->unack.lock, flags);
+
+	to_remove = skb_queue_len(&h5->unack);
+
+	seq = h5->tx_seq;
+
+	while (to_remove > 0) {
+		if (h5->rx_ack == seq)
+			break;
+
+		to_remove--;
+		seq = (seq - 1) % 8;
+	}
+
+	if (seq != h5->rx_ack)
+		BT_ERR("Controller acked invalid packet");
+
+	i = 0;
+	skb_queue_walk_safe(&h5->unack, skb, tmp) {
+		if (i++ >= to_remove)
+			break;
+
+		__skb_unlink(skb, &h5->unack);
+		kfree_skb(skb);
+	}
+
+	if (skb_queue_empty(&h5->unack))
+		del_timer(&h5->timer);
+
+	spin_unlock_irqrestore(&h5->unack.lock, flags);
+}
+
 static void h5_handle_internal_rx(struct hci_uart *hu)
 {
 	BT_DBG("%s", hu->hdev->name);
@@ -146,17 +185,24 @@ static void h5_handle_internal_rx(struct hci_uart *hu)
 static void h5_complete_rx_pkt(struct hci_uart *hu)
 {
 	struct h5 *h5 = hu->priv;
-	u8 pkt_type;
+	const unsigned char *hdr = h5->rx_skb->data;
 
 	BT_DBG("%s", hu->hdev->name);
 
-	pkt_type = h5->rx_skb->data[1] & 0x0f;
+	if (H5_HDR_RELIABLE(hdr)) {
+		h5->tx_seq = (h5->tx_seq + 1) % 8;
+		h5->tx_ack_req = true;
+	}
 
-	switch (pkt_type) {
+	h5->rx_ack = H5_HDR_ACK(hdr);
+
+	h5_pkt_cull(h5);
+
+	switch (H5_HDR_PKT_TYPE(hdr)) {
 	case HCI_EVENT_PKT:
 	case HCI_ACLDATA_PKT:
 	case HCI_SCODATA_PKT:
-		bt_cb(h5->rx_skb)->pkt_type = pkt_type;
+		bt_cb(h5->rx_skb)->pkt_type = H5_HDR_PKT_TYPE(hdr);
 
 		/* Remove Three-wire header */
 		skb_pull(h5->rx_skb, 4);
@@ -193,7 +239,7 @@ static int h5_rx_payload(struct hci_uart *hu, unsigned char c)
 
 	BT_DBG("%s 0x%02hhx", hu->hdev->name, c);
 
-	if ((hdr[0] >> 4) & 0x01) {
+	if (H5_HDR_CRC(hdr)) {
 		h5->rx_func = h5_rx_crc;
 		h5->rx_pending = 2;
 	} else {
@@ -217,8 +263,15 @@ static int h5_rx_3wire_hdr(struct hci_uart *hu, unsigned char c)
 		return 0;
 	}
 
+	if (H5_HDR_RELIABLE(hdr) && H5_HDR_SEQ(hdr) != h5->tx_seq) {
+		BT_ERR("Out-of-order packet arrived (%u != %u)",
+		       H5_HDR_SEQ(hdr), h5->tx_seq);
+		h5_reset_rx(h5);
+		return 0;
+	}
+
 	h5->rx_func = h5_rx_payload;
-	h5->rx_pending = ((hdr[1] >> 4) & 0xff) + (hdr[2] << 4);
+	h5->rx_pending = H5_HDR_LEN(hdr);
 
 	return 0;
 }
@@ -412,13 +465,13 @@ static struct sk_buff *h5_build_pkt(struct h5 *h5, bool rel, u8 pkt_type,
 
 	h5_slip_delim(nskb);
 
-	hdr[0] = h5->next_ack << 3;
-	h5->txack_req = false;
+	hdr[0] = h5->rx_seq << 3;
+	h5->tx_ack_req = false;
 
 	if (rel) {
 		hdr[0] |= 1 << 7;
-		hdr[0] |= h5->next_seq;
-		h5->next_seq = (h5->next_seq + 1) % 8;
+		hdr[0] |= h5->tx_seq;
+		h5->tx_seq = (h5->tx_seq + 1) % 8;
 	}
 
 	hdr[1] = pkt_type | ((len & 0x0f) << 4);
@@ -461,7 +514,7 @@ static struct sk_buff *h5_prepare_pkt(struct h5 *h5, u8 pkt_type,
 
 static struct sk_buff *h5_prepare_ack(struct h5 *h5)
 {
-	h5->txack_req = false;
+	h5->tx_ack_req = false;
 	return NULL;
 }
 
@@ -505,7 +558,7 @@ static struct sk_buff *h5_dequeue(struct hci_uart *hu)
 unlock:
 	spin_unlock_irqrestore(&h5->unack.lock, flags);
 
-	if (h5->txack_req)
+	if (h5->tx_ack_req)
 		return h5_prepare_ack(h5);
 
 	return NULL;